Cold hardiness & minimum temperature

Is String of Spades (Ceropegia woodii 'Heartless')cold hardy? Hardiness zone & min temp

Also called Ceropegia Heartless.

More about string of spades

About String of Spades

Ceropegia woodii 'Heartless' · also called Ceropegia Heartless · houseplant

Ceropegia woodii 'Heartless', or String of Spades, is a trailing semi-succulent whose leaves are elongated and pointed like a spade rather than a rounded heart, with silver marbling over green. It cascades from baskets and forms bead-like tubers along the stems. Care matches the rosary vine: bright indirect light, gritty soil, dry-down watering, and ASPCA pet-safe.

Cold limit: USDA 10-12 (grown indoors in most US homes) · RHS H1c (18-26°C)

Watch for — Overwatering and tuber rot: Soft, translucent, mushy leaves and rotting stems signal soggy soil. Use gritty mix, let it dry almost fully between waterings, and cut back sharply in winter.

What string of spades's hardiness rating actually means

String of Spades is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-12 (grown indoors in most US homes) — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about 5 °C (and never frost). String of Spades has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for string of spades as it gets too cold:

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can string of spades go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when string of spades can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

String of Spades hardiness — frequently asked questions

Is string of spades cold hardy?

String of Spades is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. String of Spades can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (grown indoors in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature string of spades can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). String of Spades has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is string of spades?

String of Spades is rated USDA 10-12 (grown indoors in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can string of spades survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to string of spades below its minimum temperature?

Below about about 5 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.